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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 147 · 40 sums
TalentJR

The method (Threes make cubes): Cube: n × n × n. Cube root: the number that, used three times, gives the cube. Units digits: 1→1, 2→8, 3→7, 4→4, 5→5, 6→6, 7→3, 8→2, 9→9, 0→0 — use them to guess cube roots. Make a perfect cube: break into primes; multiply by what completes each group of three (or divide by what is left over). A big cube of edge a cut into small cubes of edge b gives (a ÷ b)³ small cubes.

NameDateTime takenScore ___ / 40
  1. 1.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  2. 2.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.Which of these is a perfect cube? (a) 523 (b) 512 (c) 531
  4. 4.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  5. 5.What is 7³? =
  6. 6.Which of these is a perfect cube? (a) 2365 (b) 2539 (c) 2197
  7. 7.What is ∛125? =
  8. 8.What is 11³? =
  9. 9.What is ∛8? =
  10. 10.What is ∛1728? =
  11. 11.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  12. 12.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  14. 14.Which of these is a perfect cube? (a) 1580 (b) 1331 (c) 1508
  15. 15.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  18. 18.What is 5³? =
  19. 19.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  20. 20.What is 8³? =
  21. 21.What is ∛1000? =
  22. 22.Which of these is a perfect cube? (a) 3641 (b) 3555 (c) 3375
  23. 23.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  24. 24.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  25. 25.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  26. 26.What is ∛4096? =
  27. 27.Which of these is a perfect cube? (a) 1044 (b) 1189 (c) 1000
  28. 28.What is ∛512? =
  29. 29.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  30. 30.What is 16³? =
  31. 31.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  32. 32.What is 12³? =
  33. 33.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  34. 34.Which of these is a perfect cube? (a) 240 (b) 274 (c) 216
  35. 35.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  36. 36.Which of these is a perfect cube? (a) 2961 (b) 2744 (c) 3303
  37. 37.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  39. 39.What is 6³? =
  40. 40.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?

Answer key

  1. 9
  2. 125
  3. 512
  4. 7
  5. 343
  6. 2197
  7. 5
  8. 1331
  9. 2
  10. 12
  11. 3
  12. 125
  13. 8
  14. 1331
  15. 8
  16. 64
  17. 216
  18. 125
  19. 49
  20. 512
  21. 10
  22. 3375
  23. 8
  24. 9
  25. 8
  26. 16
  27. 1000
  28. 8
  29. 18
  30. 4096
  31. 9
  32. 1728
  33. 13
  34. 216
  35. 25
  36. 2744
  37. 19
  38. 49
  39. 216
  40. 2

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